Identification of microRNAs responsive to nicotine exposure Project Summary/Abstract The genetic basis and regulatory mechanism of nicotine exposure remains largely unclear. This project aims to elucidate a novel molecular mechanism - the microRNA- regulated gene expression following the exposure to nicotine in C. elegans, a model organism for study nicotine exposure. microRNAs (miRNAs) are a group of recently identified small RNA molecules, which regulate the expression of more than 30% of protein-coding genes in human and are involved in almost all biological and metabolic processes. Although miRNAs have been found to regulate expression of genes that are related to drug exposure, the role of miRNAs under nicotine exposure has never been systemically investigated. In this project, we will employ C. elegans as a model organism to study the response of miRNAs to nicotine exposure and miRNA-mediated gene network. First, we will use the powerful Illumina's high throughput sequencing to genome-widely identify miRNAs differentially expressed following nicotine exposure. Then, we will use the quantitative real-time PCR (qRT-PCR) to confirm the expression of responsive miRNAs and investigate the dose-dependent response of miRNAs. To elucidate the function of nicotine induced/repressed miRNAs, we will predict the miRNA targets using at least two well-established computational programs. The predicted miRNA targets will then be validated by the Ambion's pMIR-REPORT luciferase reporter system. To further understand the role of miRNAs during nicotine exposure, GO and KEGG pathway analyses will be employed to investigate the biological processes and corresponding genetic pathways/networks. This study is innovative and will provide new insights into the role and regulatory mechanism of miRNAs during nicotine exposure. This project will also have the potential to provide a novel miRNA-based biomarker for monitoring the exposure and health effect of nicotine exposure/addictive/abuse.